You are not a waste of space!!!
The question you are wrestling with -- 'Who am I?', is something so many people ask themselves at some point in their lives. Even Oprah did a series of shows on this very question. You can find references to this idea throughout our literature -- which tells me that humans have been asking this question for a very long time.
It sounds like you are on a journey of self-discovery, which is a beautiful thing. It can be *really* scary, but try to remember that the only part of the journey you can do anything about is the NOW.
Figuring out who you are will come, but for now, try to asking yourself 'What do I need right this moment?' It could be something as simple as realizing you're thirsty and getting a glass of water.